Electrical brush contact device



Jan. 1, 1952 G. R. LUM 2,581,256

ELECTRICAL BRUSH CONTACT DEVICE Filed June 25, 1946 4 Sheets-Sheet l FIG.

l/EN 70/? G. R. L UM "27? 686 SAW/d ATTORNEY Jan. 1, 1952 G. R. LUM 2,581,266

ELECTRICAL BRUSH CONTACT DEVICE Filed June 25, 1946 4 Sheets-Sheet 2 //v VEN ran 6. R. L UM 5/ %QC M ATTORNEY Jan. 1, 1952 G. R. LUM 2,581,266

ELECTRICAL BRUSH CONTACT DEVICE Filed June 25, 1946 4 Sheets-Sheet 4 FIG. /0 44 7 INVENTOR V G. R. LUM

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ATTORNEY Patented Jan. 1, 1952 ELECTRICAL BRUSH CONTACT DEVICE George Renwick Lum, New York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 25, 1946, Serial No. 679,111

12 Claims.

This invention relates to electrical connecting means and more particularly to electrical connecting means forming electrical connections between relatively movable parts.

An object of the invention is to provide improved electrical connecting means for relatively movable parts of an electrical device.

A feature of the invention resides in a shaft receiving element which provides a support for terminals and frictional contact means.

Another feature resides in contact means supported on the shaft receiving element.

Other features reside in the structures and arrangements of parts in the electrical connecting means.

The invention provides an improved electrical connecting means suitable for use in electrical potentiometers in which wiper contacts are required to be electrically connected to terminals.

In the drawings:

Fig. l is a plan view of an electrical potentiometer in which the invention is embodied, a cover member on the potentiometer being partly broken away to disclose parts normally covered by the cover member;

Fig. 2 is an enlarged view, partly in section, of a portion of the potentiometer shown in Fig. 1;

Fig. 3 is an enlarged view, in section, of a portion of the potentiometer shown in Fig. 1 and taken on the line 3-3 in Fig. 2;

Fig. 4 is a View, in section, taken on the line 4-4 in Fig. 3;

Fig. 5 is an enlarged view, in elevation, of the shaft receiving element with terminals and contact means supported thereon;

Fig. 6 is a top view, partly in section, of the shaft receiving element shown in Fig. 5;

Fig. 7 is a view, corresponding, in general, to Fig. 6 but with certain parts of the device relatively moved from the positions shown in Fig. 6;

Fig. 8 is a top plan view of a portion of Fig. 7 but with some of the parts slightly moved;

Fig. 9 is an edge view of the portion shown in Fig. 8;

Fig. 10 is an enlarged view, in elevation, of the shaft receiving element mounted on a portion of the shaft and shows a pile-up of portions of arms and arm supports mounted on the upper portion of the shaft; and

Fi 11 is an exploded view of the shaft receiving element and shows one of the contact means and a terminal therefor.

The electrical connecting means of this invention is useful in various electrical devices in which conducting members carried on a stem or shaft are required to be in frictional engagement with other conducting members of the electrical device while the shaft is rotated or when there is relative rotation of certain other parts of the electrical device and the shaft. Electrical potentiometers are often required in which wiper contacts are arranged to frictionally sweep over concentrically arranged resistance elements and transmit potentials to terminals or other conductors in the potentiometer. With the understanding that it is not a limitation of the invention the present invention is shown in the drawings as being embodied in a potentiometer. The potentiometer may be constructed along the general lines of a potentiometer shown and described in a patent application identified as L. N. Hampton-O. S. A. Mesch-C. V. Obst, Serial No. 661,246, filed April 11, 1946, now Patent No. 2,578,353 issued December 11, 1951.

The potentiometer I2 as shown in Fig. 1 comprises a cup-type body l3 and a removable cover It. The body 13 is constructed to provide spaced annular walls [5, l6, ll, I8 and I9 extending upwardly from a base wall 20 shown in Figs. 2 and 3. The spaced annular walls I5, l5, ll, 18 and I9 and the base wall 20 cooperatively define annular spaces 2!, 22, 23 and 24 in which resistance elements 25, 26, 21 and 28 are respectively set, the resistance elements 25, 26, 21 and 28 comprising in each case as shown in Fig. 3 a cardlike support 29 with a resistance wire 35 wound thereon. The resistance elements 25, 26, 2'! and 28 are mounted edgewise in the body 13 and are held in place at spaced points by means of wedge devices 3| which are located in the annular spaces 2i, 22, 23 and 24. The wedge devices 35 form no part of the present invention but their function is to urge spaced points of the resistance elements toward the associated annular walls 7 in the body l3 and maintain the resistance elements in the required annular spaces in the body 13. Spacers 32 are provided between the inner face of each resistance element 25, 2t, 2? and 28 and the annular wall toward which the resistance element is urged by the wedge device 3! and at some points wedge sticks 33 are located between the inner face of the resistance element and the associated annular wall in the body 13.

The resistance elements 25, 26, 27 and 28 are arranged so that upper edges of the resistance elements will be frictionally engaged by wiper contacts 34, 35, 36 and 37, respectively. Leadout wires 38 are connected to the resistance elements 25, 26, 2! and 28 and. are extended through apertures 33 formed in the base wall 25, the leadout wires 38 serving as outside leads for the resistance elements in the potentiometer ii.

The wiper contacts 95, 35, 99 and 31 are insulatingly supported on arms 49, 42 and 43, respectively which are mounted on a shaft 44 supported and arranged in the body 63 so that the shaft 44 and the body i3 are relatively rotatable. A tubular hub portion 45 is provided in the central portion of the body l3 to accommodate the shaft 44, the tubular hub portion 45 being located inwardly of an annular wall 49 which is located inwardly of the annular wall l9. The walls i9 and 49 extend upwardly from the base wall 29 and are further connected by spokes 4? shown in Figs. 1 and 2. The wall 45 and the hub portion 45 are connected by a horizontal wall 49 in which spaced apertures 99 are formed. The wall 45, the hub portion 45 and the horizontal wall 48 cooperatively define spaces 59 and 5! which are. in communication through the spaced apertures 49. The upper surface of the horizontal wall 49 is bevelled where it meets the annular wall 46 to provide a slope 52 extending downwardly from the wall 99 to the apertures 49.

Supported in the upper end of the hub portion 45 is a flanged bearing and supported in the lower end of the hub portion 45 is a flanged bearing 54, the bearings 53 and 59 being constructed to accommodate the shaft 44 and serve as bearing members therefor. The shaft 44 is provided with a conical bearing portion 55 which is in frictional bearing engagement with the flanged bearing 53, the flanged bearing 55 having formed therein a seat 55 to accommodate the conical bearing portion 55 on the shaft 44. The upper portion 5'! of the shaft 94 is smaller in diameter than other portions of the shaft and is formed to provide, at spaced points, longitudinally extending slots 58. A well 59 is formed in the upper portion 51 of the shaft M to accommodate plates 59, a spring 5!, a plunger 62 and a ball 53. The plates 59, the spring 6!, the plunger 62 and the ball 93 are placed in the well 59 in the order mentioned and so that ,1

the spring 6! will tend to urge the plunger 92 and the ball 63 toward the top of the well 59. A retainer ring 64 is set into groove 55 to prevent the ball 53 from rising entirely out of the well 59. The ball 93 and. the plunger 62 may be pressed downwardly in the well 59 against the action of the spring 9|. The upper end of the shaft 49 is screw threaded at 95 to receive a nut Bl which serves as a retainer means for a stack of parts mounted on the upper portion 5? of the shaft 44. The stack of parts mentioned comprise an insulating tube 69, a washer 59, portions 19, ll, 12 and E3 of arms 43, 42, 4| and 49, respectively, arm holders [4, l5, l6 and l! and. washers l8 and 19. The arms 49, M, 42 and 53 as above mentioned provide supports for the wiper contacts 34, 35, 36 and 3! respectively and except for length are alike in structure. The ar mholders I4, l5, l6 and H are alike in structure and an understanding of the structures of the arms 49, 4|, 42 and 49 and the arm holders I4, 15, I6 and H may be had by consideration of the structures of the arm 43 and arm. holder 74 shown in Fig. 2.

The arm 43 shown in Fig. 2 comprises a plate portion 89, an arm portion 8! which is channel shaped in cross-section and a body portion 82. The body portion 82 as shown in Fig. 2 is aper, tured to receive the shaft 44 and is made like an incomplete ring so that it may be sprung op n.

to accommodate the shaft 44 and is provided with inwardly extending spaced projections 93 to frictionally engage the shaft 44. An upwardly extend ing flange 84 is provided on the outer edge portions of the arm portion 8| and the body portion 82. The arm holder 14 has a flanged body porion 85 and a flanged arm portion 99, the body portion 85 being constructed to fit over the body portion 82 and the arm portion 89 being coirstructed to fit over the arm portion 9| above described. The body portion 95 is provided with inwardly extending lugs 8! to engage in the Slots. 58 formed in the shaft 44. The arm 49 is releasably secured to its arm holder "i5 by a bolt or other suitable fastening means 98. The body portions of the arm 43 and the arm holder 14 cooperatively define a space 89, shown in Fig. 3, to accommodate portions of a lead wire 99 which is extended from a heel portion 9| of the wiper contact 31 and to a conducting ring 99 which will be subsequently described. The lead wire 90 is an insulated lead wire and a portion of it is snubbed around a post 92' mounted on the arm 43. One end of the conductor of the lead wire 99 is electrically connected to the wiper contact 31 and the other end is electrical- 1y connected to the conducting ring 93. For each wiper contact there is an arm and an arm holder constructed along the lines of the arm 43 and the arm holder 14, respectively. Con ducting rings 94, 95 and 99 are provided as conducting rings for the respective Wiper contacts 36, 35 and 34.. 4,

The conducting rings 93, 94, 95 and 99 are 61 mensioned to accommodate the insulating sleeve 68 and are, arranged in stack formationcn the insulating sleeve'68 together with washers 9'! and 98 which are alternated with the conducting rings and serve to hold the conducting rings 93, 94, 95 and 96 in spaced relation. The washers. 9'! are made of insulating material and form insulating barriers between the conducting rings. Passageways 99 are formed in insulating sleeve 69 to accommodate portions of the lead wires extending from the wiper contacts the conducting rings, each conducting ring 93, 95, 95 and 96 having a lug I99 formed on its inner surface and extending into a passageway 99 to meet and be electrically connected to the conductor of the lead wire.

The wiper contact 31 is electrically connected to the conducting ring 93. by means of the lead wire 99 which extends through the space 89 and through one of the passageways 99 to a lug 09 on the conducting ring 93. The wiper contact 39 is electrically connected to the conducting ring 94 by means of the lead wire it! which extends between the arm, H and the arm holder 15 and through a passageway 99 to a lug 199 on the conducting ring 94 as shown in Fig. 3. The wiper contacts 35 and 34 are electrically connected to the respective conducting rings 95 and 99 by means of the respective lead wires Hi2 and I03 which like the. lead wires 99 and HH extend through passageways 99 to the required conducting rings.

Peripherally grooved contact rings I94, I95, I96 and I9! are attached to and supported on the outer surfaces of the conducting rings 93, 94, 95 and 96, respectively. When the shaft 44 is rotated in the body l3 the wiper contacts 34, 35 36. and. 31 are. movedalong the respective resistance elements. 25, 26, 2'! and 29- and frictionallyengage turns of the resistance wires on the resistance elements. The conducting rings 93.

94, 95 and 96 and the peripherally grooved contact rings I04, I05, I06 and I01 are rotated when the shaft 44 is rotated. Electrical potentials obtained in the operation of the potentiometer are conducted from the resistance elements 25, 26, 21 and 28 to the,,contact rings I07, I06, I05 and I04 respectively by way of the respective conducting rings 96, 95, 94 and 93.

The electrical connecting means of the present invention provides a means for taking on electrical potentials coming to the peripherally grooved contact rings I04, I05, I06 and I01. The electrical connecting means is identified in the drawings by a general number I08 and is shown in whole and in part in Figs. 3, 4, 5, 6, 7, 8, 9,

and 11.

The electrical connecting means I08 as shown in Figs. 10 and 11 comprises two parts I09 and H0 of insulating material and an assembly II I of conducting parts and spring means. The assembly II I comprises a flexible conductor H2, 9. terminal H3 and a spfing II4. The flexible conductor !I2 and the spring II 4 are connected at their ends to cooperatively form an expansible and contractile hOOp which may be expanded to receive the insulating part I09. The flexible conductor II2 may be any flexible conductor found suitable for the purpose but is shown in the drawings as a braided wire having eye tips H5 secured to its ends. The spring II4 may be any expansible and contractible member found suitable for the purpose but is shown in the drawings as a helical spring having hook portions I I6 formed on its ends and hooked into the eye tips II 5 on the flexible conductor II 2. The terminal I I3 is a strip of conducting material secured at one end to the flexible conductor I I2 and having an end portion II'I' to which a circuit wire, not shown, may be connected.

The part I09 of the electrical connecting means I08 is a supporting body for other parts of the connecting means and will hereinafter be called the body I 09. The body I 09 is constructed to rest on the hub portion 45 in the potentiometer body I3 and is tubular in form and has spaced annular grooves H7, H8, H9 and I formed in its outer cylindrical surf-ace I2I. A portion of the base of each annular groove 1 to I20, inclusive, is apertured to provide an elongated aperture extending through the inner surface I22 of the body I 09. The aperture formed in each annular groove II! to I20 is relatively long and is of suficient width to readily allow a flexible conductor II 2 of the assembly II I to pass into the space defined by the inner surface I 22" of the body I09.

The part I I0 of the electrical connecting means I 06 is a flanged sleeve of insulating material and will hereinafter be called the sleeve I I0. The sleeve I I0 is constructed for mounting in the body I99 and comprises a barrel portion I23 and a flange portion I24. The barrel portion I23 is constructed to readily enter the space defined by the body I09 and is of sufflcient internal diameter. to readily accommodate the contact rings I94,"

I05, I06 and I07. The flange portion I24 is constructed and arranged to rest on the top of the body I09 and has a notch I25 formed in its outer edge to be brought into register with a notch I26 formed in the outer edge of an upper flange I27 on the body I09. Spaced apertures I28, I29 and I30. and spaced and relatively large notches I3I,

' I32, I33 and I34 are formed in the flange portion I24 of the sleeve I I0.

Elongated apertures I35, I36, I31 and I38 are formed in the barrel portion I23 of the sleeve I I0 to match with the respective elongated apertures I39, I40, MI and I42 formed in the bases of the annular grooves III, I I8, H9 and I 20 in the body I 09. The elongated apertures I35, I36, I31 and I38 follow the curvature of the barrel portion I 23 of the sleeve I I0 and the elongated apertures I39, I40, MI and I42 follow the curvature of the body I09.

The elongated apertures I35, I36, I37, I38, I39, I40. MI and I42 are of equal length and extend a considerable distance measured around the circumference of the parts in which they are formed. Considered in a counterclockwise direction the elongated aperture I36 is in an advanced position relative to the elongated aperture I and the remaining elongated apertures I31 and I38 are each in advanced positions relative to the preceding elongated apertures. Also considered in a counterclockwise direction the elongated aperture I in the body I09 is in an advanced position relative to the elongated aperture I39 and the remaining elongated apertures MI and I42 are each in advanced positions relative to the preceding elongated apertures.

When the sleeve H0 is placed within the body I99 and so that the flange I24 on the sleeve IIO rests on the flange I21 of the body I09 the elongated apertures I35, I36, I31 and I38 in the sleeve III] are in the same planes as the respective elongated apertures I39, I40, MI and I42 in the body I09. By rotatably adjusting the sleeve III! in the body I09 the elongated apertures I35, I36, I31 and I38 in the sleeve I I0 may be brought into or out of register with the respective elongated apertures I 39, I 40, I 4| and I42 in the body I09 as required. The notches I3I, I32, I33 and I34 provide convenient gripping points for a spanner wrench, not shown, but which may be used in rotatably adjusting the sleeve H0 in the body I09.

Each annular groove II I to I20, inclusive, in the body I 09 provides a receptacle in which a flexible conductor H2 and a spring II 4 of an assembly III may rest. The hoop cooperatively formed by the flexible conductor I I2 and the spring H4 is somewhat smaller in circumference than the circumference of the base of any annular groove in the body I09 and the spring II4 must be stretched when the assembly III is mounted on the body I 09 with the sleeve H0 in the body I09 and when the elongated apertures I35 to I38 in the sleeve III) are not in register with the respective corresponding elongated apertures I39 to I42 in the body I09. Assuming, however, that the flexible conductor II 2 and the spring II4 of the assembly I I I are in the annular groove I I l in the body I 09 and the sleeve I I0 is rotated to bring the elongated aperture I35 in the sleeve IIOinto full register with the elongated aperture I39 in the body I09 the spring I I4 will cause the flexible conductor II 2 to move through the elongated apertures I39 and I35 and to such position that the flexible conductor I I2 extends across the space defined by the inner surface of the barrel portion I23 of the sleeve IIO. By relatively rotating the sleeve I I0 and the body I 09 to bring the elongated apertures I35 and I39 out of register the flexible conductor I I 2 may be moved out of the space since in this operation an unapertured portion of the sleeve I I0 comes into register with the elongated aperture I39 in the body I09 and, in doing so, forces the flexible conductor I I2 outwardly against the action of the spring II4.

In "the potentiometer shown and described to explain the invention the assembly III serves as a conducting take-off for one of the contact rings carried by the rotatable shaft 04. The number of contact rings and the number of assemblies I I I employed will depend on the requirements of no case. The potentiometer shown and described oontains four contact rings I00, I05, I06 and It? for each of which an electrical take-01f is provided involving an assembly III. As shown in Figs. 3 and 10 the rotatable shaft 40 extends through the electrical connecting means I08, a portion of the rotatable shaft 40 extending through the sleeve I I mounted in the body I09.-

The contact rings I04, I05, I06 and I0! are in the space defined by the inner surface of the sleeve IIII.

Four electrical take-oil assemblies III, I53, I04 and I45 which are alike except for the length of one portion of a terminal are mounted on the body 09. The assemblies I43, I04 and I05 have respectively flexible conductors Hi0, I01 and I48 which correspond to the flexible conductor I I2 in the assembly III and also have respectively terminals I00, I50 and I5I. which correspond to the terminal II3 of the assembly III except that there is some difference in the length of an offset portion I52 provided on each terminal. It will be seen in Fig. 1-0 that the springs II I of the take-off assemblies III, I03, I00 and I35 are in the respective annular grooves H1, H8, H9 and IE0 of the body I09 and that the. springs II -'I are of sufficient diameter to prevent the springs H0 from passing through the elongated apertures I39, I09, I II and I I-2 in the body I09 and through the respective elongated apertures I35, I36, I31 and I33 in the sleeve III) when the elongated apertures I39, I00, Id! and I52 are in register with the respective elongated apertures I35, I36, I37 and I30. In Fig. the flexible conductors H2, It? and I08 are shown as drawn through the respective elongated apertures I35, I31 and I33 in the sleeve H0. It will also be understood that the flexible conductor I46 is drawn through the elongated apertures I00 and I30 when the parts are in the positions shown. In Fig. '7 the flexible conductors H2, I06, I II and I08 may be seen extending across the space defined by the inner surface of the sleeve H0.

When the sleeve I II) and the body I00 are relatively rotated so that the elongated apertures in those parts are brought out of register the flexible conductors II2, I40, I-Il and I43 are moved outwardly, against the action of the springs II i, by unapertured portions of the sleeve IIO until the flexible conductors no longer cross the space defined by the inner surface of the sleeve H0 and are entirely in the respective annular grooves I I1, H3, III) and I23 in the body I09. Fig. 6 shows the space defined by the inner surface of the sleeve I it entirely clear of the flexible conductors. Under this condition the rotatable shaft 40 together with the contact rings I04, I05, I06 and 201 conducting rings 93, 90, 95 and 96 and the insulating tube I38 may be withdrawn from or ntered in the electrical connecting means I08. It will be obvious that the flexible conductors I I2, Ice, Mi and I03 may be brought into and out of electrical connection with the respective contact rings I03, I05, I00 and III? as required simply by relatively rotating the sleeve I I0 and the body I09 to required positions.

A releasable latch I53 is provided to hold the sleeve I It in the body I09 and to hold the sleeve rotated relative to the body I09 to such position that the flexible conductors H2, I00, I41 and I48 mitted to the respective terminals H3,

extend across the space defined by the inner surface of the sleeve and in contact with the respective contact rings I04, I05, I00 and I0! when the rotatable shaft M and the parts carried thereby are in required operating positions in the body I3 of the potentiometer I2. The releasable latch I53 as shown in Figs. 5, '7, 8 and 9 comprises a spring wire with a staple end portion I55 extending through a groove I55 formed in the under surface of the flange I of the sleeve H0 and into the apertures I28 and I29 in the flange I24. A free portion I56 of the latch I53 extends in bowed form over a portion of the upper surface of the flange I20 and to the notch I and then extends downwardly in a portion I51 across outer edge portions of the flange I20 and the upper flange IZ'I on the body I09 and terminates in a backwardly extending bowed free end portion I58 arranged in bearing engagement with the under surface of the upper flange I2? on the body I09 to hold the sleeve IIO against undue rising in the body I09. The notches I25 and I20 in the sleeve H0 and the body I09 respectively are arranged so that they will be in register when the sleeve H0 is in such position relative to the body I09 that the elongated apertures I35, I36, I31 and I38 in the sleeve IIO are in register with the respective elongated apertures I39, I l-0, MI and I42 in the body I09. When the notches I25 and I26 come into register the tension in the bowed portion I50 of the latch I53 causes the portion I5'I to snap into the notches I25 and I26 to prevent undesired relative rotation of the sleeve H0 and the body I09. The latch I53 may be operated to release the latched parts for relative movement by applying a suitable force to the bowed portion I56 of the latch. The bowed portion I56 extends across the aperture I in the flange I24 to facilitate engagement of the bowed portion I56 by a suitable hand tool, not shown, but which may be any device suitable for engaging the latch I53 to move the portion I5'I from the notches I25 and When the shaft 44 and the contact rings I00, I05, I00 and IIII are in required position in the electrical connecting means I08 and the sleeve H0 is positioned relative to the body I03 so that the flexible conductors H2, I06, I0! and its extend through the respective elongated apertures I39, I00, MI and I02 in the body I09 and through the respective elongated apertures I35, IS I31 and I30 in the sleeve IIEI, under the pull of the springs III, the flexible conductors II2, Ids, It! and Hit are in frictional engagement with the respective contact rings I00, I05, I00 and I0? carried by the rotatable shaft 40. (Fig. 4 shows the flexible conductor I in frictional engagement with the contact ring I05). Under this condition the potentials coming to the wiper contacts 3'5, 33, 35 and 30 and conducted by way of the respective lead wires 90, ml, I02 and I03 to the respective conducting rings 93, 50, 95 and 90 and from them to the respective contact rings I04, I05, I00 and I01 are transmitted to the flexible conductors II2, I05, I0! and I58, respectively.

The flexible conductors H2, I30, I I? and I03 are in electrical connection with the respective terminals H3, I03, I and I5I of the respective electrical take-off assemblies III, I33, I35 and I05 and the potentials coming to the flexible conductors N2, M3, I4! and I43 are therefore trans his, I and I 5I.

The terminals II3, I49, I50 and I5I are supported in spaced relation on the body I09. Each terminal is a relatively long strip of conducting material formed to have a substantially straight body portion I59 terminating at its upper end in an offset portion I52 and terminating at its lower end in an offset portion I60. The offset portions I52 and I60 on each terminal are in the same plane and are offset from the plane of the body portion I59 to form shoulders I6I and I62. A tab I63 is provided on the terminal to extend in the same plane as the body portion I59 and in parallel spaced relation with the offset portion I52. The tab I63 may be formed by striking out portions of the oifset portion I 52 and the shoulder I62 as shown in Fig. 11. The upper end of the offset portion I52 is turned inwardly to the plane of the body portion I59 to provide a top shoulder I 64 and the upper end of the terminal is formed to provide a tubular portion I65 constructed to extend around the required flexible conductor and be electrically connected to the flexible conductor. When the terminals are mounted on the body I09 the tabs I63 extend into spaced recesses I66 formed in the lower end of the body I09 as shown in Fig. 5, the offset portions I52 extend upwardly in engagement with the outer surface of the body I09 and to a required annular groove in the body I09. The shoulders I62 on the terminals extend under the lower edge of the body I 09 and the top shoulders I64 extend over flanges defining the annular grooves in the body I 09. Zhe upper end of each terminal extends into a required annular groove in the body I09 and is connected to the flexible conductor in'the required annular groove.

It will be seen, therefore, that upper portions of the terminals are mounted on the body I09 and that the body portions I 59 and oiiset portions V66 of the terminals extend considerable distances below the body I 09. When the body I09 with the terminals supported thereon is in required position in the potentiometer body I 3 and as shown in Fig. 3 the terminals extend downwardly through the body I3 between the wall 46 and the hub 45. The body portions I59 of the terminals are long enough to extend to and through apertures 49 in the horizontal wall 48 and the shoulder I6I on the terminals are positioned to snap under and engage the lower surface of the horizontal wall 48. When the terminals are being placed in the body I3 the offset portions I60 of the terminals engage the slope 52 on the horizontal wall 48 and are slightly flexed to pass through the apertures 49. Some spring pressure is developed in the terminals in moving them into the body I3 and the spring pressure causes the shoulders I6I to snap under and engage the lower surface of the horizontal wall 48 when the shoulders I6I on the terminals pass entirely through the apertures 49. Engagement of the shoulders I6I of the terminals with the lower surface of the horizontal wall 48 in the body I3 prevents undue rising of the electrical connecting means I08 in the body I3.

What is claimed is:

1. An electrical connecting means forming an electrical connection between relatively movable parts comprising a contact, a flexible conductor extending around and engageable with said contact, a terminal electrically connected to said flexible conductor, spring means attached to said flexible conductor and operable to pull said fiexible conductor into engagement with said contact, an apertured body for said flexible conductor, spring means and terminal, an apertured sleeve supported in said apertured body and extending around said contact and cooperable with.

10 said apertured support to control the engagement of said flexible conductor with said contact.

2. An electrical connecting means forming an electrical connection between relatively movable parts comprising a contact, a tubular body having an elongated aperture formed therein, a sleeve mounted in said tubular body and extending around said contact, said sleeve having an elongated aperture formed therein corresponding to the elongated aperture formed in said tubular body, said sleeve and said tubular body being relatively rotatable to bring the elongated apertures into and out of register and a flexible conductor and a spring cooperatively forming a hoop extending around and mounted on said body, said spring being operable to pull said flexible conductor through the elongated apertures in said tubular body and sleeve and into contact with said contact when the elongated apertures are in register.

3. An electrical connecting means forming an electrical connection between relatively movable parts comprising a ring contact, a tubular body, a sleeve supported in said tubular body and rotatable therein and extending around said ring contact, said tubular body and said ring contact being relatively movable, an expansible and contractile hoop extending around and in engagement with said body, said sleeve and said body having apertures formed therein to be brought into and out of register through relative movements of said tubular body and sleeve, a portion of said hoop being operable to pass through the apertures formed in said tubular body and r sleeve and into engagement with said ring contact when the apertures in said tubular body and sleeve are in register and a terminal electrically connected to said hoop and extending therefrom.

4. An electrical connecting means forming an electrical. connection between relatively movable parts comprising a ring contact, a tubular body, a sleeve supported in said tubular body and rotatable therein and extending around said ring contact, said tubular body and sleeve having elongated apertures formed therein to be brought into and out of register by relative movement of said tubular body and sleeve, 21. flexible conductor and a spring cooperatively forming an expansible and contractile hoop supported on said tubular body, said spring being operable to pull said flexible conductor through the elongated apertures in said tubular body and sleeve and into engagement with said ring contact when the elongated apertures in said tubular body and sleeve are in register and a terminal mounted on said body and having electrical connection with said flexible conductor.

5. An electrical connecting means forming an electrical connection between relatively movable parts comprising a ring contact, a support for said ring contact, a tubular body having a groove formed therein, a sleeve supported in said tubular body and extending in spaced relation around said ring contact, said body and said ring contact being relatively rotatable, the groove in said body having an aperture formed therein and extending through the inner wall of said body, said sleeve having an aperture formed therein to be brought into register with the aperture formed in the groove in said body, an expansible and contractile conducting hoop extending around said body and disposed in the groove in said body, a portion of said hoop being operable to extend through the aperture acetate lorrned in said body and through the aperture formed in said sleeve and into contact with said ring contact when the apertures in said body and sleeve are in register, said body and said sleeve being relatively rotatable to withdraw said hoop from engagement with said ring contact and a terminal supported on said body and having electrical connection with said hoop.

6. An electrical connecting means forming an electrical connection between relatively rotatable parts comprisinga grooved ring contact, a support for said ring contact, a tubular insulating body having an annular groove formed in its outer surface and having an elongated aperture formed in the groove and extending through to the space defined by said body, a tubular sleeve rotatably supported in said body and extending in spaced relation with and surrounding said ring contact, said tubular sleeve having an elongated aperture formed therein in register with said ring contact and operable to be brought into register with the elongated aperture: in said body by relative rotation of said body and sleeve, an expansible and contractile hoop mounted in the groove in said body and having a conducting portion operable to extend through the elongated apertures in said body and sleeve and into contact with said ring contact when the elongated apertures in said body and sleeve are in register and a terminal of conducting material,

mounted on said body and electrically connected to the conducting portion of said hoop.

'7. An electrical connecting means forming an electrical connection between relatively rotatable parts comprising a plurality of spaced ring contacts, a support for said ring contacts, a tubular insulating body having spaced annular grooves formed in its outer surface and having an elongated aperture formed in each groove and extending through to the space defined by said body, a sleeve rotatably supported in said body extending in spaced relation with and surrounding said ring contacts, said sleeve having elongated apertures formed therein to register with said ring contacts and operable to be brought into and out of register with the elongated apertures formed in said body, a contractile and expansible hoop supported in each annular groove in said body and having a conducting portion operable to extend through an elongated aperture in said body and an elongated aperture in said sleeve and into contact with a predetermined ring contact when the elongated apertures in said body and sleeve are in register, said body and sleeve being relatively rotatable to selectively bring the elongated apertures in said body into and out of register with the corresponding elongated apertures in said sleeve and terminals, individual to the expansible and contractile hoops, mounted on said body, each of said terminals being electrically connected to the conducting portion of the hoop it is required to serve.

8. An electrical connecting means forming an electrical connection between relativelyrotatable parts comprising a plurality of spaced contacts, a support for said contacts, a tubular body having elongated apertures formed therein and arranged in advanced positions around said body, said 'contacts and said body being relativeiy rotatable, a sleeve rotatably supported in said body and hav ing elongated apertures formed therein to match the elongated apertures formed in said body, said sleeve surrounding said contacts and expansible and contractile conducting hoops supported on iii said body and having portions operable to extend through the elongated apertures in said body and sleeve and into frictional engagement with said contacts when the elongated apertures in said body are in register with the elongated apertures in said sleeve, said body and said sleeve being relatively rotatable to bring the elongated apertures in said body into and out of register with the elongated apertures in said sleeve.

9. An electrical connecting means forming an electrical connection between relatively rotatable parts comprising a contact, a flexible conductor extending around and operable to be moved into and out of engagement with said contact, a relatively rotatable body and sleeve supporting said flexible conductor and extending around said contact, said body and contact being relatively rotatable, said body and sleeve having apertures formed therein to be brought into and out of register and providing openings through which a portion of said flexible conductor may pass to engage said contact when the apertures in said body and sleeve are in register, means to urge said flexible conductor through the apertures in said body and sleeve and into engagement with said contact and a releasable latch engaging said body and sleeve and operable to hold said body and sleeve in required position to allow said flexible conductor to extend into engagement with said contact.

10. An electrical connecting means forming an electrical connection between relatively rotatable parts comprising a contact, a relatively rotatable body and sleeve extending around said contact, said body and sleeve having elongated apertures formed therein to be brought into and out of register by relative rotation of said body and sleeve, a flexible conductor supported on said body and operable to move into and out of engagement with said contact through the elongated apertures in said body and sleeve, means to urge said flexible conductor through the elongated apertures in said body and sleeve and into engagement with said contact when said body and sleeve are relatively rotated to positions in which the elongated apertures in said body and sleeve are in register and a releasable spring latch engaging said body and sleeve and operable to hold said body and sleeve in required adjusted positions for engagement of said flexible conductor with said contact.

11. In an electrical control device, in combination, an electrical element, a support for said electrical element, a wiper contact to travel over and frictionally engage said electrical element, a shaft extending through said support and supporting said wiper contact, said support and said shaft being relatively rotatable, a ring contact carried by said shaft, a tubular body supported in said support, a sleeve rotatably supported in said tubular body and constructed to accommodate said shaftand ring contact, an expansible and contractile conducting hoop supported on said body and having a portion operable to extend through said body and sleeve and into con tact with said ring contact, said body and said sleeve having elongated apertures formed therein which may be brought into and out of register by relatively rotating said body and sleeve, the

elongated apertures being constructed to allowv passage therethrough of a portion of said conducting hoop and a terminal electrically connected to said conducting hoop and supported on said body and extending into holding engagement in said support.

12. In an electrical control device in combination a cup-type casing, spaced concentric walls extending in said casing, a connecting Wall extending across the space between two of said concentric walls, said connecting wall having spaced apertures formed therein, a body supported on an end of one of said concentric walls, electrical terminals supported on said body in spaced relation, leg portions of said terminals extending through the apertures in said connecting wall and ofiset shoulders formed on said leg portions at points where said leg portions extend through the apertures in said connecting wall, said oilset shoulders being in snapped-over engagement with said connecting wall to hold said body in said casing.

GEORGE RENWICK LUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

